for example, the departure at 15.42 and the arrival at
16.23, and a return flight departs at 08.10 and arrives at
17.51. <- is there an answer for this test case which is
mentioned in the problem text.

Give me please one sample test case, this task looks like
an easy one.

pay attention to float point error!

int(0.12*100)=11!

> pay attention to float point error!
>
> int(0.12*100)=11!

I wrote a test case, not an answer...?